Transgender transition is a process by which transsexual and transgender individuals switch from one gender presentation to another, often change their social gender roles, legal names, and legal sex designation. Transsexual people are often defined as those who undergo sex reassignment surgery, although some in the transgender community reject this definition. Transgender transition is an individualized process. Some individuals require hormone therapy and multiple surgical procedures for their transition to be successful, some may require no medical intervention at all, and others may require some conservative medical interventions.

Many use the terms sex reassignment therapy, "sex reassignment” or "sex reassignment surgery" (aka SRS) to describe these medical procedures. However, many in the transgender community find these terms offensive. Implicit in the word"reassignment" is the idea that someone other than the self can "assign" or otherwise decide a person's gender. This is in clear conflict with the concept of "gender identity" which is a person's internal knowledge of their own gender. Many transgender and transsexual individuals feel strongly that their internal sense of their gender - their gender identity- is not subject to the assignment or reassignment by others. While some feel that the term "sex reassignment surgery" would more accurately be called "genital reassignment surgery" or "genital reconstruction surgery", it is important to note that the surgeries related to transgender transition go beyond the genitalia, and that the medical procedures go beyond surgery.

"Transgender transition services" is an umbrella term for all medical procedures and services related to the sex/gender transition of both transgender individuals and some individuals born with intersex conditions, and include the various medical treatments and procedures that alter an individual's primary and/or secondary sexual characteristics. While these services are considered medically necessary interventions for many transgender persons who experience the deep distress of body dysphoria, all of these services and procedures are also performed on other men and women for other, not dissimilar, reasons. Services may include hormone replacement therapy (HRT), various surgical procedures (see below), removal of facial and/or body hair for transwomen (aka epilation usually accomplished with electrolysis or laser hair removal), the provision of prosthetic devices (e.g. breast or penile prostheses), and voice retraining. This may also include services provided by a mental health professional either as a requirement of transgender transition or simply to aid an individual through the transition process.